Pulmonary Langerhans cell histiocytosis (PLCH) is a rare sporadic cystic lung disease of unknown aetiology that is characterised by the infiltration and destruction of the wall of distal bronchioles by CD1a + Langerhans-like cells. In adults, PLCH is frequently isolated and affects young smokers of both sexes. Recent multicentre studies have led to the more standardised management of patients in clinical practice. Smoking cessation is essential and is occasionally the only suitable intervention. Serial lung function testing is important because a significant proportion of patients may experience an early decline in forced expiratory volume in 1 s and develop airflow obstruction. Cladribine was reported to dramatically improve progressive PLCH in some patients. Its efficacy and tolerance are currently being evaluated. Patients who complain of unexplained dyspnoea with decreased diffusing capacity of the lung for carbon monoxide should be screened for pulmonary hypertension by Doppler echocardiography, which must be confirmed by right heart catheterisation. Lung transplantation is a therapeutic option for patients with advanced PLCH. The identification of the BRAF V600E mutation in approximately half of Langerhans cell histiocytosis lesions, including PLCH, and other mutations of the mitogen-activated protein kinase (MAPK) pathway in a subset of lesions has led to targeted treatments (BRAF and MEK (MAPK kinase) inhibitors). These treatments need to be rigorously evaluated because of their potentially severe side-effects.

https://err.ersjournals.com/content/errev/26/145/170070.full.pdf

How I manage pulmonary Langerhans cell histiocytosis

Birt-Hogg-Dube syndrome (BHD) is an autosomal dominant genodermatosis with malignant potential characterized by cutaneous and extracutaneous stigmata. Aberrations in the folliculin (FLCN) gene, which is located on chromosome 17, have been discovered in individuals with this condition. Over 150 unique mutations have been identified in BHD. The skin lesions associated with this condition include fibrofolliculomas, trichodiscomas, perifollicular fibromas, and acrochordons. Extracutaneous features of the syndrome typically include the lung (spontaneous pneumothorax and cysts) and the kidney (neoplasms). The only malignancies associated with BHD are renal cancers; however, other tumors have been observed in individuals with BHD. In this article, the skin lesions associated with this condition are reviewed, lung and renal manifestations associated with this syndrome are presented, and malignancies occurring in these patients are summarized.

Birt–Hogg–Dubé Syndrome: A Review of Dermatological Manifestations and Other Symptoms

Lung cysts are commonly seen on computed tomography (CT), and cystic lung diseases show a wide disease spectrum. Thus, correct diagnosis of cystic lung diseases is a challenge for radiologists. As the first diagnostic step, cysts should be distinguished from cavities, bullae, pneumatocele, emphysema, honeycombing, and cystic bronchiectasis. Second, cysts can be categorized as single/localized versus multiple/diffuse. Solitary/localized cysts include incidental cysts and congenital cystic diseases. Multiple/diffuse cysts can be further categorized according to the presence or absence of associated radiologic findings. Multiple/diffuse cysts without associated findings include lymphangioleiomyomatosis and Birt-Hogg-Dube syndrome. Multiple/diffuse cysts may be associated with ground-glass opacity or small nodules. Multiple/diffuse cysts with nodules include Langerhans cell histiocytosis, cystic metastasis, and amyloidosis. Multiple/diffuse cysts with ground-glass opacity include pneumocystis pneumonia, desquamative interstitial pneumonia, and lymphocytic interstitial pneumonia. This stepwise radiologic diagnostic approach can be helpful in reaching a correct diagnosis for various cystic lung diseases.

/pdf/a-stepwise-diagnostic-approach-to-cystic-lung-diseases-for-1034fp2wlh.pdf

A Stepwise Diagnostic Approach to Cystic Lung Diseases for Radiologists.

An Algorithmic Approach to the Interpretation of Diffuse Lung Disease on Chest CT Imaging: A Theory of Almost Everything.

Birt-Hogg-Dube (BHD) syndrome is an uncommon, autosomal dominant, multiorgan systemic disorder manifesting as cutaneous fibrofolliculomas, lung cysts with or without spontaneous pneumothorax, and renal tumors. Spontaneous pneumothorax and lung cysts on chest computed tomography (CT) should lead to the inclusion of BHD syndrome in the differential diagnosis, because these findings may develop earlier than other clinical manifestations. Here, we review and describe the characteristic findings of BHD syndrome. The number, shape, size, and distribution of the lung cysts can help to differentiate BHD syndrome from other diffuse cystic lung diseases. Knowledge of the chest CT findings of BHD syndrome may lead to a correct diagnosis and the initiation of an appropriate work-up in order to prevent pneumothorax and for the early detection of renal tumors.

Birt-Hogg-Dubé syndrome: characteristic CT findings differentiating it from other diffuse cystic lung diseases.

Cystic Lung Diseases: Algorithmic Approach

429: stroke code overuse or misuse - a need for structured support systems

A 34-year-old female presented with fever and abdominal pain. Past medical history includes Crohn's and Behcet's disease. Examination revealed multiple skin ulcerations, oral aphthae, and bilateral coarse rales. She developed respiratory distress with diffuse bilateral alveolar infiltrates on chest radiograph requiring intubation. PaO2/FiO2 ratio was 132. The chest computed tomography revealed extensive nodular and patchy ground-glass opacities. Bronchoalveolar lavage demonstrated a predominance of neutrophils. Methylprednisolone 60 mg every 6 h and broad-spectrum antimicrobials were initiated. No infectious etiologies were identified. Surgical lung biopsy demonstrated diffuse alveolar damage (DAD) mixed with lymphocytic and necrotizing vasculitis with multiple small infarcts and thrombi consistent with Behcet's vasculitis. As she improved, steroids were tapered and discharged home on oral cyclophosphamide. Pulmonary involvement in Behcet's is unusual and commonly manifests as pulmonary artery aneurysms, thrombosis, infarction, and hemorrhage. Lung biopsy findings demonstrating DAD are consistent with the clinical diagnosis of adult respiratory distress syndrome. The additional findings of necrotizing vasculitis and infarcts may have led to DAD.

Ravikanth Vydyula

Papers

Cystic Lung Diseases: Algorithmic Approach

429: stroke code overuse or misuse - a need for structured support systems

Surgical lung biopsy to diagnose Behcet's vasculitis with adult respiratory distress syndrome.